This invention relates to a press for pressing metal sheets, particularily to a new support structure which holds the upper mold for a press brake or the like.
Conventionally, a press brake forms a designed product by holding the material to be formed between the upper mold fixed to a movable ram through its holder and a lower mold fastened on the table for pressing the material by up and down motion of the movable ram.
In the case of a press brake of larger size, however, where the table is long and the shoulders at both ends of the movable ram are at the end parts of the table, the clearance between the upper and the lower molds at the center part of the ram becomes wider than that at both end parts inasmuch as the hydraulic cylinders press the shoulders at both ends of the ram is such that the center part of the upper mold retracts in pressing the material, resulting in the degradation in accuracy of the product.
Various attempts have been made to prevent this retraction of the upper mold at the center part of the ram, such as providing several hydraulic cylinders near the center part of the movable ram or using liners to adjust the clearance between the two molds. Neither of such remedies successfully adjust the clearance between the molds precisely. Besides, taking too much time for the accompanying adjustment is another disadvantage.
Accordingly, an object of this invention is to provide a press consisting of arranging several adapters on the lower side edge of a movable ram to adjust the relative position of the ram to the holder by turning an eccentric shaft member incorporated in the adapted, thereby keeping the clearance between the upper and lower molds constant over the entire length of the ram during the operation to greatly improve the precision of the formed product.
Hereinafter the invention will be described with references to the accompanying drawings which show a preferred embodiment.